The present invention relates to dynamoelectric machines and more specifically to an apparatus and method for aligning stacked laminations of a dynamoelectric machine for use in either or both stator and rotor of such machine.
It is long known in the prior art of dynamoelectric machines in assembling laminations, typically between approximately forty sixty steel plates per inch, for stator and rotor cores of such machines to hold the assembled stacked lamination plates together along the axial dimension by either or both welding and cleating. It also is long known in the prior art to generally utilize displaced segments in the typical steel laminations, such segments being arranged to nestingly engage in complementary openings in adjacent laminations when the laminations are assembled in stacked relationship. This general type of arrangement for stator cores can be seen in long expired U.S. Pat. No. 3,202,851, issued to W. J. Zimmerle et al on Aug. 24, 1965. In this patent, cuts or slits are provided in each lamination and an arcuate interlock bridge portion is die punched therebetween to include a flattened portion raised from the planar surface of the lamination and connected thereto by opposed, stretched metallic angularly disposed shoulders. The bridge portion is then wedged into tight engagement with a compatible opening of an adjacent stacked lamination prior to an annealing treatment of the stacked lamination assembly. In later U.S. Pat. Nos. 4,149,309, issued on Apr. 17, 1979; No. 4,160,182, issued on Jul. 3, 1979; No. 4,280,275, issued on Jul. 28, 1981; and No. 4,438,558, issued on Mar. 27, 1984; all to Yoshiaki Mitsui, FIG. 4 of each of these patents discloses a similar arcuate interlock bridge portion formed in each lamination, and, as in the Zimmerle patent, the bridge portion is force fit into tight engagement with a compatible opening of an adjacent lamination. Still later U.S. Pat. No. 4,538,345, issued to Arthur Dieterichs on Sep. 3, 1985, teaches tapered or angular displaced lamination segments nesting in press fit relation with compatible openings in adjacent laminations. In this patent, bent tabs are utilized along the lamination perimeters ensure minimum axial separation prior to annealing of the lamination stack with a final axial pressing step being utilized to bend back the tabs after annealing. Finally, in U.S. Pat. No. 4,979,285, issued to Benson D. Martin on Dec. 25, 1990, angularly displaced segments are once again utilized to frictionally engage through applied pressure with compatible recesses of adjacent laminations.
In accordance with the present invention, it has been recognized that past stacked lamination assemblies in the art which have utilized the general principle of displacing lamination segments in the laminations to nest with compatible openings in adjacent laminations have failed to consider let alone minimize core losses in the nesting areas. In fact, the prior art has failed to recognize that application of pressure in the nesting areas creates core loss problems. Further, the prior art has failed to recognize problems of lateral shifting in stacked laminations which can result with the use of angularly shaped nesting bridges. On the other hand, the present invention not only recognizes these problems of the prior art but further recognizes the importance of maximizing close lamination alignment by simultaneously accomplishing certain select steps in the manufacturing operations. With the recognition and resolution of past prior art problems, the present invention provides a unique apparatus and method for avoiding, or at least minimizing, past problems in the art.
In accordance with the present invention, a novel and unobvious lamination stacking arrangement for a dynamoelectric machine is provided which is economical, straightforward and efficient in both manufacture and assembly and which avoids or at least minimizes the undesirable past problems associated with welding, cleating, riveting and gluing by eliminating the need for such. Further, the present invention avoids the need for undesirably piercing of the metallic laminations and substantially reduces detrimental magnetic effects and core losses in the stacked lamination assembly. In accordance with still another feature of the arrangement of the present invention, it is possible to obtain accurate alignment of stacked laminations, with minimum metal-to-metal frictional engagement which inhibits the annealing effect in lamination assembly and which results in high core loss due to lamination sticking and frequent short circuiting of magnetic flux paths in assembled laminations.
Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein.